Must Read : Why are there black people in this world?

You know that fiery life giving ball of light in the sky? The big bright one?

Yeah, this fucking guy right here.

Anyway, something you may not know is that besides providing heat and light and all that stuff, the sun also wants to murder you. Murder you with radiation and bleach your bones

with its undying rays.

So, what's a hairless bipedal early human to do, faced with such a determined killer? Well, luckily for them evolution selected for darker, murder radiation resistant skin tones, and all was well. They probably had skin like these Massai cricket players.

Look at those guys. The sun can't do shit to them.

Next those early humans started to spread out across the world, still armoured with their radiation battling skin. Here's a reconstruction based on DNA of a 9,000 year old body found in England:

Now that's the face of a dude ready to battle the fucking sun.

There was a problem though: this sweet skin armour worked too well in areas away from the equator, and now our intrepid explorers weren't getting enough vitamin D. A few gene mutations and some evolutionary selection later, and the world now had some pasty dudes ready to soak up the sun. That guy up there might've been ready to fight the death rays, but his descendants no longer needed their defenses.

Here's a guy scrambling for every last bit of vitamin D he can get.

This change in skin tone happened all over the world as people adapted to their new sun situation, and those who lived in hot, sunny places were dark, while people farther from the equator were lighter skinned. This picture shows the range pretty well, from sun battlers to vitamin D deprived creatures huddled in a snowbank:

This system worked out pretty well, but we pesky humans never outgrew our ancestors' drive to explore and move around the world (or the urge to drive out/kidnap other people to different parts of the world), and now we're just everywhere regardless of where our ancestors evolved, and regardless of the power of the sun.

This guy is gonna need a glass of milk if he wants any vitamin D here.

This guy forgot his radiation armour about 50 generations ago and a continent away.

If you live in most areas of the world this isn't that big a problem, but it can be a huge problem for those who wandered back into the radiation death zone without protection. Here's what an average Australian looks like:

Versus what an aboriginal Australian looks like:

You see a difference? That difference is probably why the most common cancer for Australians under 40 is melanoma, the average Australian has a 1 in 17 chance of getting melanoma, and that this is two to three times the rate seen in Canada, the US, and the UK. Dark skin really helps in sunny places because, and I can't say this enough, the sun wants to fucking kill you.

So, to return to the original question, why are there black people in this world? Because while a big chunk of the human race went galavanting off into frigid climes and forgot what their pigmentation was for, other humans stayed where it was hot, and never forgot the true enemy.

It's dreaming of murder right now. Where's your skin armour?

Update:

It's been pointed out to me that a picture full of skinny young model types is not the most accurate view of humanity. Please enjoy this more representative demonstration of human skin tone variety as well, with examples ranging from people I'm assuming only come out at night under the soft glow of the Arctic moon, all the way up to those who would punch the sun right in its stupid throat.